Cystic fibrosis (CF) is among the most prevalent, lethal diseases of genetic origin. In this disease, abnormal ion transport across the respiratory epithelia leads to dehydrated, viscous and poorly-cleared airway secretions that contribute to chronic infection of the airways and early death. Knowles, 11 Clin. Chest. Med. 75 (1986). The action of amiloride, a diuretic, to inhibit Na.sup.+ and water absorption when applied to the luminal membrane of airway epithelia, led to the hypothesis that amiloride might inhibit excessive Na.sup.+ absorption in CF patients and thereby "liquify" airway secretions to provide a beneficial effect on mucociliary clearance and long-term pulmonary function. See, e.g., Knowles, 221 Science 1067 (1983), Waltner, 8 Trends in Pharm. Sci. 316-320 (1987). Because an effective concentration of amiloride cannot be achieved in the airway lumen by oral administration, this drug must be administered as an aerosol to achieve its therapeutic potential. The administration of amiloride as an aerosol is described in U.S. Pat. No. 4,501,729 to Boucher et al.
A pilot study has confirmed clinical benefit of amiloride aerosol when administered as a liquid aerosol. See Knowles, 332 N. Engl. J. Med. 1189 (1990). However, while the administration of a liquid aerosol provides a useful means of treatment, it also has several limitations. It is time-consuming for the patient, not easily portable, and the dosage is limited by the low solubility of amiloride in the nebulizer solution. Consequently, an object of the present invention is to further improve and refine methods for the administration of amiloride aerosols.